A large amount of research has been conducted concerning microcapsule structures, wherein various types of drugs are encapsulated in a so-called liposome composed of a lipid bilayer membrane, to be used as a material in drug delivery system (DDS). Recently, highly functional microcapsules have been developed that carry various substances (various ligands, etc.) on the surface thereof (for example, on the liposome surface).
Gene vectors (DNA vectors) for inserting a target gene (DNA, etc.) into a target cell play a major role in the field of gene therapy, for example. The development of artificial, non-virus-based gene vectors providing functionality that far surpasses that of traditional virus vectors has advanced, and more specifically, microcapsule vectors having properties that can be most suitably employed have been developed as artificial vectors.
As an example, patent document 1 describes a microcapsule (microdevice) called a multifunctional envelope-type nano device (MEND) that has been noted for its use as a gene vector. A MEND has a structure wherein a DNA core is surrounded by a lipid membrane, and expectations for its practical application are increasing because MENDs can increase the insertion rate into a target cell through modification of the lipid membrane surface with various functional molecules such as a target-binding ligand, cell membrane-penetrating peptide, and the like.
Patent document 1: Japanese Patent Application Laid-open No. 2006-167521.